81878904 has 128 divisors (see below), whose sum is σ = 243648000. Its totient is φ = 25401600.

The previous prime is 81878893. The next prime is 81878911. The reversal of 81878904 is 40987818.

It is a self number, because there is not a number n which added to its sum of digits gives 81878904.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 291244 + ... + 291524.

It is an arithmetic number, because the mean of its divisors is an integer number (1903500).

Almost surely, 2^81878904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81878904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121824000).

81878904 is an abundant number, since it is smaller than the sum of its proper divisors (161769096).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81878904 is a wasteful number, since it uses less digits than its factorization.

81878904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 386 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 45.

The square root of 81878904 is about 9048.6962596829. The cubic root of 81878904 is about 434.2341816986.

The spelling of 81878904 in words is "eighty-one million, eight hundred seventy-eight thousand, nine hundred four".